The overall goal of this neuroimaging project is to determine the anatomical basis of reduced cognition in sickle cell disease (SCD). Specifically to test the hypothesis that impaired cognition is closely associated with decreased cortical gray matter and hippocampal volumes, and is less associated with the extent of subcortical ischemia/infarction. This will be accomplished by quantitative magnetic resonance imaging (MRI), long TE proton magnetic resonance spectroscopic imaging (1H MRSI), and neuropsychological testing that will include test of executive function and memory. These tests will include the California Card Sorting Task (CCST), the Self Ordered Pointing Task, tests of written and verbal fluency and the this study will focus on adult SCD patients with Wechsler Memory Scale (WMS). no history of overt clinical stroke. Overt infarcts are known to be associated with cognitive deficits. However, SCD patients with no history of CVAs are known suffer from impairment of memory and executive function. This study is designed to test whether cortical and hippocampal degeneration subsequent to subcortical ischemia is a marker of cognitive decline in these patients with no history of stroke. The ischemia that can occur in subcortical ischemic vascular disease (SIVD) is similar to the silent infarcts seen in SCD. In SIVD it has been determined that cognitive decline is associated with decreased cortical gray matter and hippocampal volumes. This project is designed to look for similar relationships in SCD. The primary hypotheses are: 1.) Gray matter volume and gray matter NAA are significantly decreased in SCD versus control subjects. 2.) Comical gray matter and hippocampal volume and NAA will correlate highly with cognition while white matter lesions, lacunars infarcts, and white matter NAA will be less correlated with cognition. Secondary hypotheses are: 1.) Gray matter volume and NAA reductions in SCD compared with controls will be greater in the frontal lobe than in posterior areas. 2) Hippocampal volume will correlate with memory function. And frontal cortical gray matter volume will correlate with executive function.